In the multivariate logistic analysis, preoperative Hb level (odds ratio 2.25, 95% confidence interval [CI] 1.64–3.10), cardiac disease (odds ratio 0.28, 95% CI 0.14–0.55), and type of surgery (odds ratio 0.06, 95% CI 0.03–0.10) were identified as independent predictors for transfusion after TKA (Table 2). This evidence concerns the gene GSTM1 and heart disorder.